1. Field of the Invention
This invention relates to soil compacting methods and devices and, more particularly, to a method and a device for increasing the bearing capacity of soil.
2. Description of the Prior Art
Structural foundations are designed to transmit the weight of the structure to the underlying soil or rock, which serves as a basic supporting member. The foundation must be essentially unyielding, since one of the chief requirements is the minimization or the elimination of settlement due to yielding of the soil under applied loads.
Structural foundations are of two main types, namely, spread foundations and pilings.
A spread foundation is a structural element designed to distribute a concentrated load to reduce the distributed pressure to an allowable use which can safely be supported by the soil thereunder.
When the soil at or below the level where the spread foundation would normally be placed is unsuitable in some respect for a spread-foundation design, then the weight of the structure must in some manner be transferred to the soil at greater depths or to rock. Bearing piles or caissons are used for this purpose. Such piles can be friction piles, which are supported through skin friction, Gow caisson piles or end bearing piles, which rely on the firmness and strength of hard soil or rock below the surface of the soil.
Spread foundations are preferable because they are relatively inexpensive compared to piles.
However, when the safe bearing capacity or bearing value of the soil is less than the pressure applied to the soil by the foundation, then the foundation must be made of piles unless the soil can be stabilized. The most popular way to stabilize the soil is through compaction by vibrating devices or rollers. Further, by compacting the soil consolidation occurs, which is the removal of any excess water contained therein.
Present methods of compacting loose grain soil can increase the load-bearing capacity of the soil substantially. However, under the present systems, compacting soil requires extensive amounts of machinery and a considerable amount of time. The same is true for pile foundations. Also, these methods only compact the soil in the vertical direction and very little compaction or strength is achieved in the lateral direction. Further, under present systems, determining the load-bearing capacity of compacted soil is very difficult and time consuming at best.
Therefore, it is an object of our invention to compact soil quickly and inexpensively.
Further, it is an object of our invention to compact soil with a minimum amount of equipment.
It is another object of the invention to compact soil in both the lateral direction and vertical direction whereby prestressing the soil prior to submitting the soil to bearing loads and to accurately determine load-bearing capacity of the soil.